CVE-2026-52982
In the Linux kernel, the following vulnerability has been resolved: net: usb: rtl8150: fix use-after-free in rtl8150_start_xmit() syzbot reported a KASAN slab-use-after-free read in rtl8150_start_xmit() when accessing skb->len for tx statistics after…
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.54%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
In the Linux kernel, the following vulnerability has been resolved: net: usb: rtl8150: fix use-after-free in rtl8150_start_xmit() syzbot reported a KASAN slab-use-after-free read in rtl8150_start_xmit() when accessing skb->len for tx statistics after usb_submit_urb() has been called: BUG: KASAN: slab-use-after-free in rtl8150_start_xmit+0x71f/0x760 drivers/net/usb/rtl8150.c:712 Read of size 4 at addr ffff88810eb7a930 by task kworker/0:4/5226 The URB completion handler write_bulk_callback() frees the skb via dev_kfree_skb_irq(dev->tx_skb). The URB may complete on another CPU in softirq context before usb_submit_urb() returns in the submitter, so by the time the submitter reads skb->len the skb has already been queued to the per-CPU completion_queue and freed by net_tx_action(): CPU A (xmit) CPU B (USB completion softirq) ------------ ------------------------------ dev->tx_skb = skb; usb_submit_urb() --+ |-------> write_bulk_callback() | dev_kfree_skb_irq(dev->tx_skb) | net_tx_action() | napi_skb_cache_put() <-- free netdev->stats.tx_bytes | += skb->len; <-- UAF read Fix it by caching skb->len before submitting the URB and using the cached value when updating the tx_bytes counter. The pre-existing tx_bytes semantics are preserved: the counter tracks the original frame length (skb->len), not the ETH_ZLEN/USB-alignment padded "count" value that is handed to the device. Changing that would be a user-visible accounting change and is out of scope for this UAF fix.
- CVSS 3.1
- 9.8 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 0.54% probability · 44th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-416
- Affected
- linux/linux kernel
- Source
- 416baaa9-dc9f-4396-8d5f-8c081fb06d67
References
- https://git.kernel.org/stable/c/23f0e34c64acba15cad4d23e50f41f533da195faPatch
- https://git.kernel.org/stable/c/24831b0b2ada9fef18d1f486b7b7c444ee5ba637Patch
- https://git.kernel.org/stable/c/30cf9829d09ca958279c937af8e35495cd2f1e09Patch
- https://git.kernel.org/stable/c/423b5b86e14e190f6e3161eb5f2ea5f908295ba7Patch
- https://git.kernel.org/stable/c/4dd7eb94f79486b77ca6b4c8676aedbc465dc802Patch
- https://git.kernel.org/stable/c/5af290c86fa81ddbc86a08d54229af5daa40c6a4Patch
- https://git.kernel.org/stable/c/5db090ca07b28a63fb1499690cf19a3f3adafacbPatch
- https://git.kernel.org/stable/c/6999d70e0eda39af029fa1891c48f0a8832b09d5Patch
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.